Wumpus-Core is a low-level library for generating static 2D
vector pictures, its salient feature is portability due to no
FFI dependencies. It can generate PostScript (EPS) files and SVG
files. The generated PostScript code is plain and reasonably
efficient as the use of stack operations, i.e gsave and
grestore, is minimized.

Although Wumpus-Core only generates vector output, the generated
PostScript can be interpreted by GraphicsMagick or a similar
tool to convert EPS files into bitmap image files (e.g JPEGs).

Wumpus-Core makes pictures from paths and text labels. Paths
themselves are made from points. The usual affine
transformations (rotations, scaling, translations) can be
applied to Pictures. Unlike PostScript there is no notion of a
current point, Wumpus-Core builds pictures in a coordinate-free
style.

GENERAL DRAWBACKS...

For actually building pictures, diagrams, etc. Wumpus-Core is
very low-level. There is a supplementary package Wumpus-Basic
available that helps create certain types of diagram, but it is
experimental - functionality is added and dropped between
releases, it has no stable API.

Some of the design decisions made for Wumpus-Core are not
sophisticated (e.g. how path and text attributes like colour are
handled, and how the bounding boxes of text labels are
calculated), so Wumpus might be limited compared to other
systems. However, the design permits a fairly simple
implementation, which is a priority.

UPDATING to 0.40.0

Core.Picture API change - the path construction function has
changed from path to primPath. The type of the path segments
has changed, the functions lineTo and curveTo now build
AbsPathSegments and primPath consumes AbsPathSegments.

The Text API has changed substantially, however most user code
should only need minor changes. The functions writePS_latin1,
writeEPS_latin1 and writeSVG_latin1 have been removed, code
should be changed to use writePS, writeEPS and and
writeSVG respectively. These three functions no longer take a
TextEncoder argument as TextEncoders no longer exist.

The Font Size API has also changed substantially. It now
exports a more consistent set of metrics (consistent with what
is present in font files - the previous version was derived
from hand measurements). It also adds a margin to bounding box
calculations, again this is more consistent with how font files
actually work.

The handling of escaped special characters is now more
consistent and the escaping mecahnism has been clarified
(previously the documentation and the implementation were at
odds): PostScript glyph names are delimited between &
(ampersand) and ; (semi), Unicode code points are delimited
by &# (ampersand-hash) and ; (semi). Note Wumpus silently
drops mal-formed escape charcters, for robustness this is
preferable to throwing a runtime error, but it does mean the
output needs visually checking.

Changelog:

37.0 to 0.40.0:

Text handling substantially revised. SVG text output is now
better aligned to Unicode. The encoding tables for PostScript
have been re-thought, the previous implementation had some
serious design flaws that should now be rectified.

The rules for escaping special characters has been clarified.
Previously the documentation suggested
ampersand-name-semicolon could be used to escape glyph names
however only ampersand-hash-name-semicolon worked.
ampersand-name-semicolon is now the correct way. The
ampersand-hash prefix is for numeric literals -
ampersand-hash-num_literal-semicolon.

Versions of the textlabel functions have been added to
Core.Picture for escape-parsed text. It is useful for
higher-level software to escape the text, do some calculations
then render it - going back to un-escaped text for the
rendering would be inefficient.

The internal representation of paths has changed. They are now
represented as start-point plus list of relative path
segments rather than start-point plus list of absolute path
segments. Using relative path segments makes it cheaper to
move paths with translate, although calculating the bounding
box and rendering to PostScript is more expensive. The
rationale for the change is that to make complex pictures,
paths are potentially moved many times but the other
operations are only performed once.

Internal change to Primitives and the PrimCTM - ellipses and
labels no longer have a point (center or baseline left)
as an element in the datatype, the point is now represented
within the PrimCTM.

Name change to Core.Picture API - the path construction
function path has been renamed to primPath.

Name change in Core.FontSize, the function textBoundsEnc
has been renamed to textBoundsEsc. Wumpus-Core now calls
strings that have been parsed for escape characters
Escaped Text rather than Encoded Text.

Fixed bug in illustrateControlPoints where the control points
were drawn but the original primitive was lost.

Added initial support for arbitrary SVG attributes (e.g.
onmouseover handlers) via annotateGroup in Core.Picture.
Arbitrary SVG "defs" can be written into the defs prologue
by using writeSVG_defs instead of writeSVG. This
functionality is mostly untested!